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Jump to function at absolute address

Hi,

In my project I have some functions that has to be protected against changes. For that reason a checksum has to be calculated on that specific code in runtime, just to prove that the actual code is intact.

Those specific functions are built in an own outside project (just to protect it from changes) and downloaded to a dedicated area in the flash.

When the standard code wants to access this functionality in the "outside code" an absolute jump is made to the start address of this outside function (0x50000).

This seems to go right, in the "outside code" I can set some outputs to light some LEDs, so the jump seems to have gone right.

But when I try to use variables in this "outside code" nothing seems to work, I tried to make a while loop to blink a diode and counted a variable down to zero, but the variables seems corrupt.

What can be the problem? Can it be something with the memory model that makes references to variables corrupt? I don't know, I'm not so good at memory models.

Any Idea, some one ?

Regards / Rasmus